VLF SCATTERING FROM A COLUMN OF IONIZATION IN THE EARTH-IONOSPHERE WAVE-GUIDE

Choosing a highly idealized model, we analyze the scattering of VLF ra dio waves from a thin vertical column of ionization within the Earth-i onosphere waveguide. It is shown that mode conversion is produced if t he column is limited in height and/or if the ionization is a function of height. However, the relative higher-mode content would be small in some situations such as in the case of the ionization produced by a c loud-to-ionosphere lightning discharge.